[Sanghera]

How long can the Parallel Port Wire be without losing a signal. I've seen some really long extension cables.
Thanks.

[kong]

I think the one for my lathe is 4-5 meters long. It goes up the wall, across the ceiling then down the other side. No loss of signal that I know of. Actually, it then goes into a parallel port switch box, which is connected to the PC by another cable, about 1 metre long.

[CNCPlastic]

They make 25 foot printer cables and they work just fine for printing so I'm sure it would meet cnc needs. Mine is about 15 feet and works just fine.

[Shop Rag]

If the cable is shielded you can get by with 100 feet. Also be sure not to run the cable next to any electrical divices.

[Sanghera]

Why is that?
Thanks for the help.

[sol]

Long wire = antennae...picks up electrical noise from other equipment.

[Sanghera]

How do you properly shield the cable?
Thanks.

[c_nut]

Sanghera

Buy it that way. Most if not all new cables are already shielded.

Just don't run the cable parallel to any cables carrying AC or porer DC. It can cross at an angle but not run along in line with them.

[c_nut]

That was power DC. Sorry.

[Sanghera]

OK Thanks.

[CNCPlastic]

One more tip...only connect one end of the parallel cable shield to ground. I had connected both ends on my setup and suffered some very strange problems due to a ground loop issue.

[cbcnc]

CNCPlastic,

That's a good point about only connecting the cable shield to a ground only at one end.
What is the shield connected to? Is the DB-25 housing grounded?
I run a male-male cable from the lpt port to my controller board. As far as I know the female housings are grounded at both ends. I will have to check that out.
I've had some noise issues that I have traced to the switch on my trim router and I am not sure where the noise is getting into my controller.

More questions than answers.

Chris

[RotarySMP]

My shielded LPT cable is 3m long, and I have had missed steps when it sat on the AC or motor cables.

[c_nut]

Chris
Is your controlled in a metal case. If it is open the noise can go from the switch and magically get into the electronics right through space, air and plastic. Metal with all six sides closed is the only protection. And also a ground on the case. AC power line ground would be good here. Ground shielding and loops are the hardest electronic problems to cure. First move is to seperate all power and signal. From there it is a little like magic, and some times the problems go away for no reason at all. If you know anybody that does Ham Radio enlist his help. Shielding is something RF people know about. Different application same cures.

C_nut

Still in the swamps north of milepost 223 on I10.